The ordered domain patterns that form spontaneously in a wide variety of chemical and physical systems as a result of competing interatomic interactions can be used as templates for fabricating nanostructures. Here we describe a new self-assembling domain pattern on a solid surface that involves two surface structures of lead on copper. The evolution of the system agrees with theoretical predictions, enabling us to probe the interatomic force parameters that are crucial to the process.

The ability to accurately determine the elastic modulus of each layer of the human cornea is a crucial step in the design of better corneal prosthetics. In addition, knowledge of the elastic modulus will allow design of substrates with relevant mechanical properties for in vitro investigations of cellular behavior. Previously, we have reported elastic modulus values for the anterior basement membrane and Descemet’s membrane of the human cornea, the surfaces in contact with the epithelial and endothelial cells, respectively. We have completed the compliance profile of the stromal elements of the human cornea by obtaining elastic modulus values for Bowman’s layer and the anterior stroma. Atomic force microscopy (AFM) was used to determine the elastic modulus, which is a measure of the tissue stiffness and is inversely proportional to the compliance. The elastic response of the tissue allows analysis with the Hertz equation, a model that provides a relationship between the indentation force and depth and is a function of the tip radius and the modulus of the substrate. The elastic modulus values for each layer of the cornea are: 7.5 ± 4.2 kPa (anterior basement membrane), 109.8 ± 13.2 kPa (Bowman’s layer), 33.1 ± 6.1 kPa (anterior stroma), and 50 ± 17.8 kPa (Descemet’s membrane). These results indicate that the biophysical properties, including elastic modulus, of each layer of the human cornea are unique and may play a role in the maintenance of homeostasis as well as in the response to therapeutic agents and disease states. The data will also inform the design and fabrication of improved corneal prosthetics.

Bicellar mixtures, planar lipid bilayer assemblies comprising long- and short-chain phosphatidylcholine lipids in suspension, were used to form supported lipid bilayers on flat silicon substrate and on nanotextured silicon substrates containing arrays of parallel troughs (170 nm wide, 380 nm deep, and 300 nm apart). Confocal fluorescence and atomic force microscopies were used to characterize the resulting lipid bilayer. Formation of a continuous biphasic undulating lipid bilayer membrane, where the crests and troughs corresponded to supported and suspended lipid bilayer regions, is demonstrated. The use of interferometric lithography to fabricate nanotexured substrates provides an advantage over other nanotextured substrates such as nanoporous alumina by offering flexibility in designing different geometries for suspending lipid bilayers.

Received Date (will be automatically inserted ajier manuscript is accepted).Molecular self-assembly can generate elaborate two-and three-dimensional supramolecular structures through the complementary interaction of attractive and repulsive forces between molecular components and their environment.' Synthetic self-assembling systems are currently limited to the one-step creation of suprarnolecular structures from molecular components, unlike biological systems which can organize supramolecular assemblies into higher ordered structures to create tissue and functional materials of specific dimensions.z Herein, we report the first observation of a synthetically produced higher ordered self-assembled structure of lipid bilayers with self-limiting dimensions mediated by chemical recognition at the membrane surface. Transmission electron microscopic (TIM) images of the self-assembled material reveal a columnar structure of stacked lipid bilayers uniform in width with lengths spanning dozens of bilayer thickness.Previous work found that liposomes composed of a pyreneIabeled synthetic receptor lipid mixed into a distearylphosphatidylcholine (DSPC) matrix performed as highly selective optical sensors for heavy metal ions?d6 In the absence of metal ions, the liquid-phase receptor lipid separates from the solid-phase DSPC matrix, producing fluorescence spectra with large excimer emission (A= = 470 nm) and relatively small monomer emission (AM = 375 rim). Addition of di-or trivalent metal ions causes an inversion of the fluorescence emission peaks (excimer emission attenuates as the monomer emission intensifies), revealing dkpersion of the receptor lipids into the DSPC matrix upon the metrd ion recognition.Complete reversibility of the process was possible by removal of the metal ions with EDTA. Figure 1. Matrixlipid DSPCand pyrene-labeledlipid PSIDA. PSIDA(1) (a) Lehn, J.-M. Science 1993Science ,260, 1762 Whhesides, G. M.; Mathias,J. P.; Seto,C. T. Science 1991Science ,254,1312 (